Glass articles, in particular hollow glass, when being handled, filled, packaged and possibly washed before being reused, can bump into each other, producing abrasion, in particular scratches, which reduces their mechanical strength.
The surface of glass articles has already been treated in order to improve their abrasion resistance, regardless of whether these glass articles are dry or wet, for example as a result of being washed.
Thus, document U.S. Pat. No. 3,438,801 describes the treatment of glass bottles to improve their dry abrasion resistance by deposition, in a first stage, at 150.degree. C., of an aqueous solution of a diaminosilane (3-(2-aminoethyl)aminopropyltrimethoxysilane, (here called DAMO) and, in a second stage at 140.degree. C., of an aqueous emulsion of polyethylene used in combination with potassium oleate.
These glass bottles are generally intended to be labeled and, consequently, the abrasion-resistant layer applied to the surface of the glass must also allow good adhesiveness of a label by means of conventional adhesives like casein and dextrin. To obtain this good adhesiveness, as well as an appropriate abrasion resistance, U.S. Pat. No. 3,873,352 describes treating the surface of the glass with an aqueous composition containing polyethylenaminepropyltrimethoxysilane which has a molecular mass of approximately 1400 (or a mixture of this silane with a diaminosilane, DAMO) and polyethylene used in combination with potassium oleate.
It has been noted, however, that these layers have a cloudy appearance which makes the glass article unusable, and that the resistance to abrasion in the wet state is not sufficient. In addition, some of these layers do not enable labels to adhere well.
Attempts have therefore been made to form, on glass surfaces, coatings which have a good appearance and to which labels adhere well, while providing resistance to abrasion when dry and in the wet state.
There has also been research for a simple process for producing them, which can be exploited industrially, both on the production line for these glass articles and when they are recycled, for example, in order to be refilled.